A new endovascular spiral lead that takes advantage of the anatomy of the cardiac branches of the vagus nerve in the SVC was developed. VNS using ESVL produced significant HR slowing at voltages slightly below the highest pulse generator output of 7.5 V, which may be suitable for long-term implantation.

The basic design for the intrapericardial leads (IPLs) used a diamond-shaped loop for stability at the distal end and a preshaped lead body within the diamond loop in which the bipolar, nonsteroid eluting, electrodes were located (Figure 1). The electrodes were titanium nitride-coated platinum iridium, 5 mm 2 in dimension © 2015 American Heart Association, Inc. Original ArticleBackground-Endovascularly implanted leads risk vascular injury and endocarditis, and can be difficult to locate in desired positions for LV pacing. We evaluated the acute and long-term stability, electric performance and histopathology of a percutaneously placed intrapericardial lead (IPL). Methods and Results-Twelve adult mongrel dogs underwent defibrillator implants incorporating IPLs. Successful uncomplicated percutaneous implantation of an IPL was achieved in all. Early fluoroscopic shift noted with 3 of 6 of the initial version IPL-1 was not seen with the modified IPL-2. Mean±95% confidence interval bipolar capture threshold at 0.5-ms pulse width for the IPL increased from 0.69±0.14 V at implant to 1.50±0.34 V (P=0.003) at 12 weeks. The 12-week thresholds were higher for IPL compared with right ventricular endocardial leads (0.75±0.33 V; P=0.001) but not different compared with coronary sinus leads (1.33±0.58 V; P=0.994). IPL impedance increased from 742±46 Ω at implant to 1066±207 Ω at 12 weeks (P=0.007). R-wave amplitude at 12 weeks was 8.37±1.52 mV. There was no important phrenic nerve stimulation from IPL pacing. Histopathology in 8 animals showed adequate adhesion of the electrodes or mesh to the epicardium without damage to underlying vasculature. There was no evidence for late pericardial inflammation or effusion. Conclusions-The IPL demonstrated adequate stability of position and acceptable electric parameters without chronic pericardial inflammation in this canine model and offers a potential alternative to endocardial pacing leads.

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